Synergistic Antibacterial Effect of Friedelin from Diospyros curranii Merr. and Ampicillin Against Some Opportunistic Gram-Negative Bacteria

Abstract

The objectives of this research was to compare synergistic effect of friedelin, isolated from hexane extract from the root of Diospyros curranii Merr., with ampicillin. The tests were conducted against opportunistic Gram-negative bacteria, Escherischia coli ATCC 25913, Acinetobacter baumannii and Pseudomonas aeruginosa.  To determine value of fractional inhibitory concentration (FIC), the broth dilution susceptibility test was designed for detecting synergistic effect. The results were shown that MICs of ampicillin and friedelin against all bacterial isolates were 256 to 512 µM and 512 to 1024 µM, respectively.  The FICs of friedelin mixed with ampicillin were 0.25 to 0.5. Synergistic analysis of friedelin mixed with ampicillin, compared to individual drug was shown more synergistic effects against all bacteria tested.  The best synergistic effect was found against E. coli ATCC 25913 with the FIC of 0.25.  The results obtained here indicated that friedelin, isolated from the root of D. curranii, had an effective synergistic effect with ampicillin against opportunistic Gram-negative bacteria.